The nonlinearities intrinsic in all analog RF devices create limitations in total system performance of RF front ends. With the introduction of more advanced threats in the Electronic Warfare (EW) spectrum, these limitations are no longer acceptable. RF receivers have to become more linear, allowing for greater dynamic range, while transmitters need to put out as much power they can, without unwanted out-of-band emissions. Without modern linearization (digital equalization and pre-distortion) techniques, the performance of RF systems is likely to get outpaced by adversarial systems. Additionally, communication and radar systems may require simultaneous transmission and reception (STAR) capabilities, and in many cases, the high power transmitted signal will leak into the receiver, resulting in nonlinear operation and reduction in sensitivity. A system such as this, is also suitable for phased array applications where many elements are spaced closely together, and linearization may be needed to increase its overall sensitivity.
Previous solutions include designing more linear/higher power amplifiers and analog linearization. Analog linearization requires very sensitive hardware design, high design/implementation costs, and this technique is generally used for narrowband systems. Alternatively, one may be able to choose a higher power and more linear amplifier, but this may reduce the efficiency of the system, have greater SWAP-C (size, weight, power, and cost), and may not be technically feasible.
The present disclosure provides a modular, mixed-signal architecture that can estimate digital nonlinear pre-inverse or post-inverse filter coefficients in real-time for equalization or pre-distortion of RF signals using a multi-channel, reconfigurable hardware platform. The proposed system can be used in applications such as in congested and contested environments with high power interferers, as well as for STAR to reduce nonlinear effects due to high-power transmitted signal leakage. The system of the present disclosure can also be implemented on the same chip as the front end, or externally.